Per-scenario dynamic nav opt-in + Settings popup + timeline restore fixes

Dynamic navigation toggle (per scenario):
- New PS_Editor_NavUtils helpers wrap UNavigationSystemV1 / RecastNavMesh
  protected APIs (RuntimeGeneration field + bEnableDrawing) via the C++
  using-trick so we can switch the level's nav mode and toggle visualization
  without engine modifications.
- FPS_Editor_SceneData gets bUseDynamicNavigation persisted in JSON.
- SpawnManager carries the live state plus a session-only bShowNavMesh
  preference (never saved).
- SceneSerializer reads/writes the flag and applies it on load (editor mode).
- SceneLoader applies it on the gameplay path before spawning actors so
  scenarios that need runtime nav rebuild get it both in editor and at
  runtime via the project's GameMode + SceneLoader::LoadScene flow.

UI:
- New "Settings" toolbar button in both Legacy and UMG widgets opens a popup
  with two checkboxes:
    * Use Dynamic Navigation - saved per scenario, live toggle
    * Show NavMesh (P) - session only, mimics editor's P key (green nav
      visualization)
- Pawn binds P to IA_ToggleNavMesh -> SpawnManager.bShowNavMesh, in sync
  with the popup checkbox.

Timeline restore correctness:
- AddOrUpdateKeyAtCurrentTime, RemoveKey, SetKeyTime, SetKeyInterpolate now
  invalidate LastAppliedValues[TrackIndex] so a key edit isn't masked by a
  stale per-track cache entry from a previous apply.
- RestoreBaseline now prefers a key at t=0 (within epsilon) over the
  captured pre-animation baseline. Updating a t=0 key + Stop now restores
  the new value instead of snapping back to the original. Tracks without a
  t=0 key still fall back to the pre-animation baseline.

Restart simulation rewind:
- Restart() used to call Stop() + Play() but Play immediately cancelled the
  pending RequestStopSimulation timer set by Stop, so transforms were never
  restored - characters stayed where they were.
- RequestStopSimulation now takes bImmediate; when true, OnEditorBeforeSimulateStop
  still fires (so BP behaviour-reset hooks run) but StopSimulation runs
  synchronously, restoring transforms before Play() recaptures them.
- Restart inlines the reset (RestoreBaseline + immediate stop + Play) so
  rewinding actually rewinds.

Build:
- Re-add NavigationSystem to PS_Editor.Build.cs (needed for ARecastNavMesh
  + ANavigationData access in NavUtils).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Unreal/Plugins/PS_Editor/Source/PS_Editor/GameMode/PS_Editor_Pawn.cpp

@@ -13,6 +13,8 @@
 #include "GameFramework/PlayerController.h"
 #include "PS_Editor_SelectionManager.h"
 #include "PS_Editor_GroundSnap.h"
+#include "PS_Editor_NavUtils.h"
+#include "PS_Editor_SpawnManager.h"
 #include "PS_Editor_PlayerController.h"
 #include "PS_Editor_Gizmo.h"
 #include "PS_Editor_UndoManager.h"
@@ -254,6 +256,11 @@ void APS_Editor_Pawn::CreateInputActions()
 	IA_Focus = NewObject<UInputAction>(this, TEXT("IA_Focus"));
 	IA_Focus->ValueType = EInputActionValueType::Boolean;
 	EditorMappingContext->MapKey(IA_Focus, EKeys::F);
+
+	// Toggle navmesh visualization (mimics UE editor's P key)
+	IA_ToggleNavMesh = NewObject<UInputAction>(this, TEXT("IA_ToggleNavMesh"));
+	IA_ToggleNavMesh->ValueType = EInputActionValueType::Boolean;
+	EditorMappingContext->MapKey(IA_ToggleNavMesh, EKeys::P);
 }
 
 void APS_Editor_Pawn::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
@@ -301,6 +308,7 @@ void APS_Editor_Pawn::SetupPlayerInputComponent(UInputComponent* PlayerInputComp
 	EIC->BindAction(IA_Confirm, ETriggerEvent::Started, this, &APS_Editor_Pawn::HandleConfirm);
 	EIC->BindAction(IA_Cancel, ETriggerEvent::Started, this, &APS_Editor_Pawn::HandleCancel);
 	EIC->BindAction(IA_Focus, ETriggerEvent::Started, this, &APS_Editor_Pawn::HandleFocus);
+	EIC->BindAction(IA_ToggleNavMesh, ETriggerEvent::Started, this, &APS_Editor_Pawn::HandleToggleNavMesh);
 }
 
 // ---- Input Handlers ----
@@ -1460,6 +1468,20 @@ void APS_Editor_Pawn::HandleFocus(const FInputActionValue& Value)
 	OrbitDistance = TargetDistance;
 }
 
+void APS_Editor_Pawn::HandleToggleNavMesh(const FInputActionValue& Value)
+{
+	// Mimics UE editor's P key — toggles the runtime navmesh visualization. We route
+	// through SpawnManager's session-only bShowNavMesh flag so the Settings popup
+	// checkbox stays in sync.
+	APS_Editor_PlayerController* EditorPC = Cast<APS_Editor_PlayerController>(GetController());
+	if (!EditorPC) return;
+	UPS_Editor_SpawnManager* SM = EditorPC->GetSpawnManager();
+	if (!SM) return;
+
+	SM->bShowNavMesh = !SM->bShowNavMesh;
+	PS_Editor_NavUtils::SetNavMeshVisible(GetWorld(), SM->bShowNavMesh);
+}
+
 // ---- Helpers ----
 
 void APS_Editor_Pawn::SetCameraMode(EPS_Editor_CameraMode NewMode)

Unreal/Plugins/PS_Editor/Source/PS_Editor/GameMode/PS_Editor_Pawn.h

@@ -212,6 +212,9 @@ private:
 	UPROPERTY()
 	TObjectPtr<UInputAction> IA_Focus;
 
+	UPROPERTY()
+	TObjectPtr<UInputAction> IA_ToggleNavMesh;
+
 	// ---- Spline point / ChildMovable drag state ----
 	TWeakObjectPtr<AActor> DraggedSplineActor;
 	TArray<FVector> SplinePointDragInitialState;
@@ -260,6 +263,7 @@ private:
 	void HandleConfirm(const FInputActionValue& Value);
 	void HandleCancel(const FInputActionValue& Value);
 	void HandleFocus(const FInputActionValue& Value);
+	void HandleToggleNavMesh(const FInputActionValue& Value);
 
 	// ---- Focus animation state (F key, frame selection) ----
 	bool bIsFocusing = false;

Unreal/Plugins/PS_Editor/Source/PS_Editor/GameMode/PS_Editor_PlayerController.cpp

@@ -389,18 +389,23 @@ void APS_Editor_PlayerController::SetSimulationPaused(bool bPaused)
 	}
 }
 
-void APS_Editor_PlayerController::RequestStopSimulation()
+void APS_Editor_PlayerController::RequestStopSimulation(bool bImmediate)
 {
 	if (!bSimulating) return;
 
 	// If a request is already scheduled, do nothing (debounce double-clicks on Stop).
-	if (UWorld* World = GetWorld())
+	// Skip the debounce when bImmediate (Restart wants to flush right now).
+	if (!bImmediate)
 	{
-		if (PendingStopSimulationHandle.IsValid()) return;
+		if (UWorld* World = GetWorld())
+		{
+			if (PendingStopSimulationHandle.IsValid()) return;
+		}
 	}
 
 	// Fire OnEditorBeforeSimulateStop immediately on every actor so BP handlers can react
-	// while the BT is still live. Then schedule the real cut for ~500ms later.
+	// while the BT is still live. Then schedule the real cut (deferred) or run it now
+	// (immediate, used by timeline Restart).
 	if (SpawnManager)
 	{
 		for (const TWeakObjectPtr<AActor>& Weak : SpawnManager->GetSpawnedActors())
@@ -413,6 +418,21 @@ void APS_Editor_PlayerController::RequestStopSimulation()
 		}
 	}
 
+	if (bImmediate)
+	{
+		// Cancel any pending deferred stop so it doesn't fire again later.
+		if (UWorld* World = GetWorld())
+		{
+			if (PendingStopSimulationHandle.IsValid())
+			{
+				World->GetTimerManager().ClearTimer(PendingStopSimulationHandle);
+				PendingStopSimulationHandle.Invalidate();
+			}
+		}
+		StopSimulation();
+		return;
+	}
+
 	if (UWorld* World = GetWorld())
 	{
 		TWeakObjectPtr<APS_Editor_PlayerController> WeakThis(this);

Unreal/Plugins/PS_Editor/Source/PS_Editor/GameMode/PS_Editor_PlayerController.h

@@ -76,9 +76,14 @@ public:
 	/** Request a deferred stop: fires OnEditorBeforeSimulateStop immediately, then schedules
 	 *  the real StopSimulation after a grace period (500ms by default) so BT has time to
 	 *  react to whatever the BP handler does in OnEditorBeforeSimulateStop.
-	 *  Timeline Stop and the Simulate toolbar button both go through this. */
+	 *  Timeline Stop and the Simulate toolbar button both go through this.
+	 *
+	 *  @param bImmediate  If true, fire OnEditorBeforeSimulateStop and run StopSimulation
+	 *                     synchronously in the same call (no grace period). Used by
+	 *                     timeline Restart, where we want transforms restored before the
+	 *                     subsequent Play(). Defaults to false (deferred). */
 	UFUNCTION(BlueprintCallable, Category = "PS_Editor")
-	void RequestStopSimulation();
+	void RequestStopSimulation(bool bImmediate = false);
 
 	/** True while simulation is running. */
 	UFUNCTION(BlueprintCallable, Category = "PS_Editor")

Unreal/Plugins/PS_Editor/Source/PS_Editor/PS_Editor.Build.cs

@@ -33,7 +33,8 @@ public class PS_Editor : ModuleRules
 			"JsonUtilities",
 			"ProceduralMeshComponent",
 			"DesktopPlatform",
-			"AIModule"
+			"AIModule",
+			"NavigationSystem"
 		});
 
 		PrivateDependencyModuleNames.AddRange(new string[]

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneData.h

@@ -61,4 +61,11 @@ struct FPS_Editor_SceneData
 	/** Global timeline data (animation tracks + duration). Empty on legacy scenes. */
 	UPROPERTY()
 	FPS_Editor_TimelineData Timeline;
+
+	/** If true, the level's nav mesh is switched to Dynamic runtime generation when this
+	 *  scenario loads — both in the runtime editor (so spawn / move actors update nav live)
+	 *  and in gameplay (for scenarios that need runtime-built navigation). False keeps the
+	 *  cooked Static nav, which has zero runtime cost. Default: false. */
+	UPROPERTY()
+	bool bUseDynamicNavigation = false;
 };

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneLoader.cpp

@@ -10,6 +10,7 @@
 #include "PS_Editor_TimelineSubsystem.h"
 #include "PS_Editor_SpawnManager.h"
 #include "PS_Editor_PlayerController.h"
+#include "PS_Editor_NavUtils.h"
 #include "AIController.h"
 #include "BrainComponent.h"
 #include "JsonObjectConverter.h"
@@ -130,6 +131,12 @@ bool UPS_Editor_SceneLoader::LoadSceneFromData(UWorld* World, const FPS_Editor_S
 		return false;
 	}
 
+	// Apply the scenario's dynamic-navigation flag BEFORE spawning actors. If the scenario
+	// needs runtime nav generation, switching the level's RecastNavMesh to Dynamic now
+	// means the actors we're about to spawn will dirty + rebuild tiles around them. Cooked
+	// Static nav is preserved on disk for scenarios that don't need this.
+	PS_Editor_NavUtils::SetDynamicNavigationEnabled(World, SceneData.bUseDynamicNavigation);
+
 	UPS_Editor_TimelineSubsystem* TimelineSS = World->GetSubsystem<UPS_Editor_TimelineSubsystem>();
 
 	int32 SpawnedCount = 0;

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneSerializer.cpp

@@ -14,6 +14,7 @@
 #include "GameFramework/CharacterMovementComponent.h"
 #include "PS_Editor_SplineEditable.h"
 #include "PS_Editor_TimelineSubsystem.h"
+#include "PS_Editor_NavUtils.h"
 #include "JsonObjectConverter.h"
 #include "Misc/FileHelper.h"
 #include "Misc/Paths.h"
@@ -166,6 +167,12 @@ bool UPS_Editor_SceneSerializer::SaveScene(const FString& SceneName, UPS_Editor_
 		SceneData.Timeline = TimelineSS->GetData();
 	}
 
+	// Per-scenario settings — read from the SpawnManager's session state.
+	if (SpawnManager)
+	{
+		SceneData.bUseDynamicNavigation = SpawnManager->bUseDynamicNavigation;
+	}
+
 	// Convert to JSON
 	FString JsonString;
 	if (!FJsonObjectConverter::UStructToJsonObjectString(SceneData, JsonString, 0, 0, 0, nullptr, true))
@@ -438,6 +445,17 @@ bool UPS_Editor_SceneSerializer::LoadScene(const FString& SceneName, UPS_Editor_
 		}
 	}
 
+	// Per-scenario settings — push into the SpawnManager's session state and apply
+	// the dynamic-navigation switch to the level's RecastNavMesh actors right away.
+	if (SpawnManager)
+	{
+		SpawnManager->bUseDynamicNavigation = SceneData.bUseDynamicNavigation;
+		if (APS_Editor_PlayerController* EditorPC = Cast<APS_Editor_PlayerController>(GetOuter()))
+		{
+			PS_Editor_NavUtils::SetDynamicNavigationEnabled(EditorPC->GetWorld(), SpawnManager->bUseDynamicNavigation);
+		}
+	}
+
 	UE_LOG(LogTemp, Log, TEXT("PS_Editor: Scene loaded: %s (%d actors)"), *SceneName, SpawnedCount);
 	return true;
 }

Unreal/Plugins/PS_Editor/Source/PS_Editor/Spawn/PS_Editor_NavUtils.cpp

@@ -0,0 +1,61 @@
+#include "PS_Editor_NavUtils.h"
+#include "NavigationSystem.h"
+#include "NavigationData.h"
+#include "NavMesh/RecastNavMesh.h"
+#include "Engine/World.h"
+#include "Kismet/GameplayStatics.h"
+
+namespace PS_Editor_NavUtils
+{
+	// ANavigationData::RuntimeGeneration and bEnableDrawing are both protected. Local
+	// using-trick subclass to re-publish them — the C++ access check uses the static
+	// type, so a static_cast through this exposing class lets us read/write them
+	// without modifying the engine.
+	struct FNavDataAccessor : public ANavigationData
+	{
+		using ANavigationData::RuntimeGeneration;
+		using ANavigationData::bEnableDrawing;
+	};
+
+	void SetRuntimeGenerationMode(UWorld* World, ERuntimeGenerationType Mode)
+	{
+		if (!World) return;
+
+		TArray<AActor*> NavMeshActors;
+		UGameplayStatics::GetAllActorsOfClass(World, ANavigationData::StaticClass(), NavMeshActors);
+		for (AActor* A : NavMeshActors)
+		{
+			if (ANavigationData* NavData = Cast<ANavigationData>(A))
+			{
+				FNavDataAccessor* Accessor = static_cast<FNavDataAccessor*>(NavData);
+				if (Accessor->RuntimeGeneration != Mode)
+				{
+					Accessor->RuntimeGeneration = Mode;
+				}
+			}
+		}
+	}
+
+	void SetDynamicNavigationEnabled(UWorld* World, bool bDynamic)
+	{
+		SetRuntimeGenerationMode(World,
+			bDynamic ? ERuntimeGenerationType::Dynamic : ERuntimeGenerationType::Static);
+	}
+
+	void SetNavMeshVisible(UWorld* World, bool bVisible)
+	{
+		if (!World) return;
+
+		TArray<AActor*> NavMeshActors;
+		UGameplayStatics::GetAllActorsOfClass(World, ANavigationData::StaticClass(), NavMeshActors);
+		for (AActor* A : NavMeshActors)
+		{
+			if (ANavigationData* NavData = Cast<ANavigationData>(A))
+			{
+				FNavDataAccessor* Accessor = static_cast<FNavDataAccessor*>(NavData);
+				Accessor->bEnableDrawing = bVisible;
+				NavData->MarkComponentsRenderStateDirty();
+			}
+		}
+	}
+}

Unreal/Plugins/PS_Editor/Source/PS_Editor/Spawn/PS_Editor_NavUtils.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include "CoreMinimal.h"
+
+class UWorld;
+enum class ERuntimeGenerationType : uint8;
+
+/**
+ * Centralised helpers for switching the level's RecastNavMesh runtime-generation mode and
+ * toggling the runtime navmesh visualization. Used by:
+ *  - The runtime editor "Settings" popup (live toggle of dynamic nav + show navmesh)
+ *  - SceneLoader (gameplay path: applies the scenario's bUseDynamicNavigation flag)
+ *  - Scenario save/load (persists bUseDynamicNavigation in JSON)
+ */
+namespace PS_Editor_NavUtils
+{
+	/**
+	 * Switch every RecastNavMesh in the world to the requested runtime-generation mode.
+	 * Static = baked nav only, no runtime updates (fastest gameplay).
+	 * DynamicModifiersOnly = only NavModifierVolumes affect nav at runtime.
+	 * Dynamic = all collision-affecting actors update the nav mesh on spawn / move.
+	 *
+	 * Idempotent — calling with the same mode the navmesh already has is a no-op.
+	 */
+	PS_EDITOR_API void SetRuntimeGenerationMode(UWorld* World, ERuntimeGenerationType Mode);
+
+	/** Convenience: switch to Dynamic if bDynamic, Static otherwise. */
+	PS_EDITOR_API void SetDynamicNavigationEnabled(UWorld* World, bool bDynamic);
+
+	/**
+	 * Toggle the runtime navmesh visualization (mimics the editor's P key — green nav lines
+	 * + tile bounds rendered on top of the world). Affects all RecastNavMesh actors in the
+	 * world. Free in editor PIE/Standalone; in shipping packaged builds, debug rendering may
+	 * be stripped depending on build flags.
+	 */
+	PS_EDITOR_API void SetNavMeshVisible(UWorld* World, bool bVisible);
+}

Unreal/Plugins/PS_Editor/Source/PS_Editor/Spawn/PS_Editor_SpawnManager.h

@@ -75,6 +75,19 @@ public:
 	/** Notify all spawned actors that implement IPS_Editor_EditableInterface of editor mode change. */
 	void NotifyEditorModeChanged(bool bIsEditing);
 
+	// ---- Per-scenario settings (persisted in JSON) ----
+
+	/** If true, switch the level's RecastNavMesh to Dynamic runtime generation when this
+	 *  scenario is loaded — both in editor and gameplay. False = keep cooked Static nav.
+	 *  Persisted in the scenario JSON; default false. */
+	bool bUseDynamicNavigation = false;
+
+	// ---- Session-only UI preferences (NOT persisted) ----
+
+	/** If true, the navmesh is rendered at runtime (mimics the editor's P key). Personal
+	 *  visualization preference, never saved with the scenario. */
+	bool bShowNavMesh = false;
+
 	/** Tick all spawned actors that implement IPS_Editor_EditableInterface. */
 	void TickEditorMode(float DeltaTime);
 

Unreal/Plugins/PS_Editor/Source/PS_Editor/Timeline/PS_Editor_TimelineSubsystem.cpp

@@ -194,20 +194,16 @@ void UPS_Editor_TimelineSubsystem::CaptureBaselinesForAllMissingTracks()
 
 void UPS_Editor_TimelineSubsystem::RestoreBaseline()
 {
-	if (PrePlayBaseline.Num() == 0) return;
-
 	// Server-only write path (same guard as ApplyValuesAtTime).
 	if (UWorld* World = GetWorld())
 	{
 		if (World->GetNetMode() == NM_Client) return;
 	}
 
+	const float ZeroEpsilon = 0.0001f;
+
 	for (const FPS_Editor_TimelineTrack& Track : Data.Tracks)
 	{
-		const TPair<FGuid, FName> Key(Track.ActorId, Track.PropertyPath);
-		const FString* BaselineValue = PrePlayBaseline.Find(Key);
-		if (!BaselineValue) continue;
-
 		AActor* Actor = FindActorById(Track.ActorId);
 		if (!Actor) continue;
 		UObject* Target = nullptr;
@@ -215,7 +211,39 @@ void UPS_Editor_TimelineSubsystem::RestoreBaseline()
 		ResolveTarget(Actor, Track.PropertyPath, Target, Prop);
 		if (!Target || !Prop) continue;
 
-		Prop->ImportText_InContainer(**BaselineValue, Target, Target, PPF_None);
+		// Pick the value to restore:
+		//   - If the user placed a key at (or before) t=0 → use that key's value. This
+		//     matches the natural mental model where a key at t=0 sets the timeline's
+		//     starting state — and lets the user adjust it just by re-keying at t=0
+		//     (otherwise Stop would keep snapping back to the captured pre-animation
+		//     baseline forever, ignoring their edits).
+		//   - Otherwise fall back to the captured pre-animation baseline so Stop still
+		//     undoes whatever the timeline pushed (relevant for tracks whose first key
+		//     is past t=0, e.g. a property that only changes mid-timeline).
+		const FString* RestoreValue = nullptr;
+		FString KeyZeroValue;
+		for (const FPS_Editor_TimelineKey& K : Track.Keys)
+		{
+			if (K.Time <= ZeroEpsilon)
+			{
+				KeyZeroValue = K.Value;
+				RestoreValue = &KeyZeroValue;
+				// Continue scanning in case there are several keys at t≈0 — the LAST one wins
+				// (matches sort order: later same-time entries override earlier ones).
+			}
+			else
+			{
+				break; // keys are sorted by time; no need to look past t>0
+			}
+		}
+		if (!RestoreValue)
+		{
+			const TPair<FGuid, FName> BaselineKey(Track.ActorId, Track.PropertyPath);
+			RestoreValue = PrePlayBaseline.Find(BaselineKey);
+		}
+		if (!RestoreValue) continue;
+
+		Prop->ImportText_InContainer(**RestoreValue, Target, Target, PPF_None);
 		if (UActorComponent* AsComp = Cast<UActorComponent>(Target))
 		{
 			AsComp->MarkRenderStateDirty();
@@ -234,15 +262,40 @@ void UPS_Editor_TimelineSubsystem::RestoreBaseline()
 		}
 	}
 
-	// Don't clear the map — a subsequent Stop (or Restart) must still restore the same baseline.
+	// Don't clear PrePlayBaseline — subsequent Stops without a t=0 key still need it.
 	// SetData/Clear are the only resetters.
 }
 
 void UPS_Editor_TimelineSubsystem::Restart()
 {
-	// Rewind + replay from the start. Done in two steps so simulation transforms are restored
+	// Rewind + replay from the start.
-	// by Stop() before Play() re-enables AI, giving a clean "from the beginning" rerun.
+	//
-	Stop();
+	// We can't just call Stop() then Play() because Stop() goes through
+	// PlayerController::RequestStopSimulation which DEFERS the actual StopSimulation by
+	// 500ms (BT grace period). The Play() call right after cancels that pending timer
+	// AND re-enters StartSimulation early (bSimulating still true), so transforms are
+	// never restored — characters stay at their current position instead of rewinding.
+	//
+	// Fix: do the full reset synchronously here. Fire OnEditorBeforeSimulateStop (via
+	// RequestStopSimulation(bImmediate=true) so BP behaviour-reset hooks still run),
+	// then immediately StopSimulation (which restores transforms + fires
+	// OnEditorSimulateStop), then Play() to capture the rewound transforms and restart
+	// AI from the clean state.
+	bIsPlaying = false;
+	CurrentTime = 0.f;
+	LastAppliedValues.Empty();
+	LastAppliedValues.SetNum(Data.Tracks.Num());
+
+	RestoreBaseline();
+
+	if (APS_Editor_PlayerController* EditorPC = FindEditorPC(GetWorld()))
+	{
+		if (EditorPC->IsSimulating())
+		{
+			EditorPC->RequestStopSimulation(/*bImmediate=*/ true);
+		}
+	}
+
 	Play();
 }
 
@@ -364,6 +417,14 @@ bool UPS_Editor_TimelineSubsystem::AddOrUpdateKeyAtCurrentTime(AActor* Actor, co
 		if (FMath::IsNearlyEqual(Track.Keys[InsertAt].Time, CurrentTime, Epsilon))
 		{
 			Track.Keys[InsertAt].Value = CurrentValue;
+			// Invalidate the per-track applied-value cache so the next ApplyTrackAtTime
+			// re-writes the (possibly different) value instead of skipping based on the
+			// stale cache entry. Otherwise, updating a key with a value the cache happened
+			// to hold from a previous apply would silently revert the property to it.
+			if (LastAppliedValues.IsValidIndex(TrackIndex))
+			{
+				LastAppliedValues[TrackIndex].Empty();
+			}
 			OnTimelineChanged.Broadcast();
 			return true;
 		}
@@ -404,6 +465,12 @@ void UPS_Editor_TimelineSubsystem::RemoveKey(int32 TrackIndex, int32 KeyIndex)
 		Data.Tracks.RemoveAt(TrackIndex);
 		LastAppliedValues.SetNum(Data.Tracks.Num());
 	}
+	else if (LastAppliedValues.IsValidIndex(TrackIndex))
+	{
+		// Track still has keys but its surrounding keys for any time may have changed —
+		// invalidate the cache so the next apply re-writes the correct value.
+		LastAppliedValues[TrackIndex].Empty();
+	}
 	OnTimelineChanged.Broadcast();
 }
 
@@ -413,6 +480,10 @@ void UPS_Editor_TimelineSubsystem::SetKeyInterpolate(int32 TrackIndex, int32 Key
 	FPS_Editor_TimelineTrack& Track = Data.Tracks[TrackIndex];
 	if (!Track.Keys.IsValidIndex(KeyIndex)) return;
 	Track.Keys[KeyIndex].bInterpolate = bInterpolate;
+	if (LastAppliedValues.IsValidIndex(TrackIndex))
+	{
+		LastAppliedValues[TrackIndex].Empty();
+	}
 	OnTimelineChanged.Broadcast();
 }
 
@@ -428,6 +499,10 @@ void UPS_Editor_TimelineSubsystem::SetKeyTime(int32 TrackIndex, int32 KeyIndex,
 	{
 		return A.Time < B.Time;
 	});
+	if (LastAppliedValues.IsValidIndex(TrackIndex))
+	{
+		LastAppliedValues[TrackIndex].Empty();
+	}
 	OnTimelineChanged.Broadcast();
 }
 

Unreal/Plugins/PS_Editor/Source/PS_Editor/UI/Widgets/PS_Editor_MainWidget.cpp

@@ -1,6 +1,7 @@
 #include "PS_Editor_MainWidget.h"
 #include "PS_Editor_SelectionManager.h"
 #include "PS_Editor_SpawnManager.h"
+#include "PS_Editor_NavUtils.h"
 #include "PS_Editor_SceneSerializer.h"
 #include "PS_Editor_SceneLoader.h"
 #include "PS_Editor_UndoManager.h"
@@ -500,6 +501,110 @@ TSharedRef<SWidget> UPS_Editor_MainWidget::RebuildWidget()
 				]
 			]
 		]
+		// Settings popup (per-scenario nav option + session navmesh visu)
+		+ SOverlay::Slot()
+		.HAlign(HAlign_Center)
+		.VAlign(VAlign_Center)
+		[
+			SAssignNew(SettingsPopup, SBorder)
+			.Visibility(EVisibility::Collapsed)
+			.BorderImage(BrushGlassStrong.Get())
+			.Padding(FMargin(28.0f, 20.0f))
+			[
+				SNew(SVerticalBox)
+				+ SVerticalBox::Slot().AutoHeight().HAlign(HAlign_Center).Padding(0.0f, 0.0f, 0.0f, 16.0f)
+				[
+					SNew(STextBlock)
+					.Text(FText::FromString(TEXT("Settings")))
+					.Font(FCoreStyle::GetDefaultFontStyle("Bold", 14))
+					.ColorAndOpacity(FLinearColor::White)
+				]
+				+ SVerticalBox::Slot().AutoHeight().Padding(0.0f, 4.0f)
+				[
+					SNew(SHorizontalBox)
+					+ SHorizontalBox::Slot().AutoWidth().VAlign(VAlign_Center).Padding(0.0f, 0.0f, 8.0f, 0.0f)
+					[
+						SNew(SCheckBox)
+						.IsChecked_Lambda([this]() -> ECheckBoxState
+						{
+							if (UPS_Editor_SpawnManager* SM = SpawnManager.Get())
+							{
+								return SM->bUseDynamicNavigation ? ECheckBoxState::Checked : ECheckBoxState::Unchecked;
+							}
+							return ECheckBoxState::Unchecked;
+						})
+						.OnCheckStateChanged_Lambda([this](ECheckBoxState State) { OnUseDynamicNavigationToggled(State); })
+					]
+					+ SHorizontalBox::Slot().FillWidth(1.0f).VAlign(VAlign_Center)
+					[
+						SNew(SVerticalBox)
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Use Dynamic Navigation")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Bold", 11))
+							.ColorAndOpacity(FLinearColor::White)
+						]
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Rebuild navmesh at runtime when actors are spawned/moved (saved with scenario).")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Regular", 9))
+							.ColorAndOpacity(FLinearColor(0.7f, 0.7f, 0.7f))
+							.AutoWrapText(true)
+						]
+					]
+				]
+				+ SVerticalBox::Slot().AutoHeight().Padding(0.0f, 8.0f, 0.0f, 4.0f)
+				[
+					SNew(SHorizontalBox)
+					+ SHorizontalBox::Slot().AutoWidth().VAlign(VAlign_Center).Padding(0.0f, 0.0f, 8.0f, 0.0f)
+					[
+						SNew(SCheckBox)
+						.IsChecked_Lambda([this]() -> ECheckBoxState
+						{
+							if (UPS_Editor_SpawnManager* SM = SpawnManager.Get())
+							{
+								return SM->bShowNavMesh ? ECheckBoxState::Checked : ECheckBoxState::Unchecked;
+							}
+							return ECheckBoxState::Unchecked;
+						})
+						.OnCheckStateChanged_Lambda([this](ECheckBoxState State) { OnShowNavMeshToggled(State); })
+					]
+					+ SHorizontalBox::Slot().FillWidth(1.0f).VAlign(VAlign_Center)
+					[
+						SNew(SVerticalBox)
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Show NavMesh (P)")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Bold", 11))
+							.ColorAndOpacity(FLinearColor::White)
+						]
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Render the navmesh in green (mimics editor's P key). Personal preference, never saved.")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Regular", 9))
+							.ColorAndOpacity(FLinearColor(0.7f, 0.7f, 0.7f))
+							.AutoWrapText(true)
+						]
+					]
+				]
+				+ SVerticalBox::Slot().AutoHeight().HAlign(HAlign_Center).Padding(0.0f, 16.0f, 0.0f, 0.0f)
+				[
+					SNew(SButton)
+					.ButtonStyle(StyleFlatButton.Get())
+					.OnClicked_Lambda([this]() -> FReply { CloseSettingsPopup(); return FReply::Handled(); })
+					[
+						SNew(STextBlock)
+						.Text(FText::FromString(TEXT("Close")))
+						.Font(FCoreStyle::GetDefaultFontStyle("Bold", 11))
+						.ColorAndOpacity(FLinearColor::White)
+					]
+				]
+			]
+		]
 
 		// ============= COMMAND PALETTE (modal, Ctrl+K) =============
 		+ SOverlay::Slot()
@@ -987,6 +1092,26 @@ TSharedRef<SWidget> UPS_Editor_MainWidget::BuildSceneButtons()
 						.Font(FCoreStyle::GetDefaultFontStyle("Regular", 10))
 					]
 				]
+				// Settings button
+				+ SHorizontalBox::Slot()
+				.AutoWidth()
+				.Padding(4.0f, 0.0f, 0.0f, 0.0f)
+				[
+					SNew(SButton)
+					.ButtonStyle(StyleFlatButton.Get())
+					.ToolTipText(FText::FromString(TEXT("Open scenario / session settings (dynamic nav, navmesh visu).")))
+					.OnClicked_Lambda([this]() -> FReply
+					{
+						OpenSettingsPopup();
+						return FReply::Handled();
+					})
+					[
+						SNew(STextBlock)
+						.Text(FText::FromString(TEXT("Settings")))
+						.Font(FCoreStyle::GetDefaultFontStyle("Regular", 10))
+						.ColorAndOpacity(FLinearColor(0.8f, 0.8f, 0.8f))
+					]
+				]
 				+ SHorizontalBox::Slot()
 				.AutoWidth()
 				.Padding(4.0f, 0.0f, 0.0f, 0.0f)
@@ -3207,6 +3332,43 @@ void UPS_Editor_MainWidget::CancelBaseLevelPopup()
 	PendingBaseLevelSelection.Empty();
 }
 
+void UPS_Editor_MainWidget::OpenSettingsPopup()
+{
+	if (SettingsPopup.IsValid())
+	{
+		SettingsPopup->SetVisibility(EVisibility::Visible);
+	}
+}
+
+void UPS_Editor_MainWidget::CloseSettingsPopup()
+{
+	if (SettingsPopup.IsValid())
+	{
+		SettingsPopup->SetVisibility(EVisibility::Collapsed);
+	}
+}
+
+void UPS_Editor_MainWidget::OnUseDynamicNavigationToggled(ECheckBoxState State)
+{
+	UPS_Editor_SpawnManager* SM = SpawnManager.Get();
+	if (!SM) return;
+
+	const bool bEnabled = (State == ECheckBoxState::Checked);
+	SM->bUseDynamicNavigation = bEnabled;
+	bSceneDirty = true;
+	PS_Editor_NavUtils::SetDynamicNavigationEnabled(GetWorld(), bEnabled);
+}
+
+void UPS_Editor_MainWidget::OnShowNavMeshToggled(ECheckBoxState State)
+{
+	UPS_Editor_SpawnManager* SM = SpawnManager.Get();
+	if (!SM) return;
+
+	const bool bVisible = (State == ECheckBoxState::Checked);
+	SM->bShowNavMesh = bVisible;
+	PS_Editor_NavUtils::SetNavMeshVisible(GetWorld(), bVisible);
+}
+
 void UPS_Editor_MainWidget::OnCloseClicked()
 {
 	if (CloseConfirmOverlay.IsValid())

Unreal/Plugins/PS_Editor/Source/PS_Editor/UI/Widgets/PS_Editor_MainWidget.h

@@ -134,6 +134,13 @@ private:
 	void ConfirmBaseLevelSelection();
 	void CancelBaseLevelPopup();
 
+	// Global Settings popup (per-scenario nav option + session-only navmesh visu).
+	TSharedPtr<SWidget> SettingsPopup;
+	void OpenSettingsPopup();
+	void CloseSettingsPopup();
+	void OnUseDynamicNavigationToggled(ECheckBoxState State);
+	void OnShowNavMeshToggled(ECheckBoxState State);
+
 	// Transform fields
 	TSharedPtr<SEditableTextBox> LocX, LocY, LocZ;
 	TSharedPtr<SEditableTextBox> RotX, RotY, RotZ;

Unreal/Plugins/PS_Editor/Source/PS_Editor/UI/Widgets/PS_Editor_MainWidget_Legacy.cpp

@@ -1,6 +1,7 @@
 #include "PS_Editor_MainWidget_Legacy.h"
 #include "PS_Editor_SelectionManager.h"
 #include "PS_Editor_SpawnManager.h"
+#include "PS_Editor_NavUtils.h"
 #include "PS_Editor_SceneSerializer.h"
 #include "PS_Editor_SceneLoader.h"
 #include "PS_Editor_UndoManager.h"
@@ -448,6 +449,124 @@ TSharedRef<SWidget> UPS_Editor_MainWidget_Legacy::RebuildWidget()
 					]
 				]
 			]
+		]
+		// Settings popup (per-scenario nav option + session navmesh visu)
+		+ SOverlay::Slot()
+		.HAlign(HAlign_Center)
+		.VAlign(VAlign_Center)
+		[
+			SAssignNew(SettingsPopup, SBorder)
+			.Visibility(EVisibility::Collapsed)
+			.BorderImage(FCoreStyle::Get().GetBrush("WhiteBrush"))
+			.BorderBackgroundColor(FLinearColor(0.08f, 0.08f, 0.08f, 0.97f))
+			.Padding(FMargin(28.0f, 20.0f))
+			[
+				SNew(SVerticalBox)
+				// Header
+				+ SVerticalBox::Slot().AutoHeight().HAlign(HAlign_Center).Padding(0.0f, 0.0f, 0.0f, 16.0f)
+				[
+					SNew(STextBlock)
+					.Text(FText::FromString(TEXT("Settings")))
+					.Font(FCoreStyle::GetDefaultFontStyle("Bold", 14))
+					.ColorAndOpacity(FLinearColor::White)
+				]
+				// Use Dynamic Navigation (saved per-scenario)
+				+ SVerticalBox::Slot().AutoHeight().Padding(0.0f, 4.0f)
+				[
+					SNew(SHorizontalBox)
+					+ SHorizontalBox::Slot().AutoWidth().VAlign(VAlign_Center).Padding(0.0f, 0.0f, 8.0f, 0.0f)
+					[
+						SNew(SCheckBox)
+						.IsChecked_Lambda([this]() -> ECheckBoxState
+						{
+							if (UPS_Editor_SpawnManager* SM = SpawnManager.Get())
+							{
+								return SM->bUseDynamicNavigation ? ECheckBoxState::Checked : ECheckBoxState::Unchecked;
+							}
+							return ECheckBoxState::Unchecked;
+						})
+						.OnCheckStateChanged_Lambda([this](ECheckBoxState State)
+						{
+							OnUseDynamicNavigationToggled(State);
+						})
+					]
+					+ SHorizontalBox::Slot().FillWidth(1.0f).VAlign(VAlign_Center)
+					[
+						SNew(SVerticalBox)
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Use Dynamic Navigation")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Bold", 11))
+							.ColorAndOpacity(FLinearColor::White)
+						]
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Rebuild navmesh at runtime when actors are spawned/moved (saved with scenario).")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Regular", 9))
+							.ColorAndOpacity(FLinearColor(0.7f, 0.7f, 0.7f))
+							.AutoWrapText(true)
+						]
+					]
+				]
+				// Show NavMesh (session-only)
+				+ SVerticalBox::Slot().AutoHeight().Padding(0.0f, 8.0f, 0.0f, 4.0f)
+				[
+					SNew(SHorizontalBox)
+					+ SHorizontalBox::Slot().AutoWidth().VAlign(VAlign_Center).Padding(0.0f, 0.0f, 8.0f, 0.0f)
+					[
+						SNew(SCheckBox)
+						.IsChecked_Lambda([this]() -> ECheckBoxState
+						{
+							if (UPS_Editor_SpawnManager* SM = SpawnManager.Get())
+							{
+								return SM->bShowNavMesh ? ECheckBoxState::Checked : ECheckBoxState::Unchecked;
+							}
+							return ECheckBoxState::Unchecked;
+						})
+						.OnCheckStateChanged_Lambda([this](ECheckBoxState State)
+						{
+							OnShowNavMeshToggled(State);
+						})
+					]
+					+ SHorizontalBox::Slot().FillWidth(1.0f).VAlign(VAlign_Center)
+					[
+						SNew(SVerticalBox)
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Show NavMesh (P)")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Bold", 11))
+							.ColorAndOpacity(FLinearColor::White)
+						]
+						+ SVerticalBox::Slot().AutoHeight()
+						[
+							SNew(STextBlock)
+							.Text(FText::FromString(TEXT("Render the navmesh in green (mimics editor's P key). Personal preference, never saved.")))
+							.Font(FCoreStyle::GetDefaultFontStyle("Regular", 9))
+							.ColorAndOpacity(FLinearColor(0.7f, 0.7f, 0.7f))
+							.AutoWrapText(true)
+						]
+					]
+				]
+				// Close button
+				+ SVerticalBox::Slot().AutoHeight().HAlign(HAlign_Center).Padding(0.0f, 16.0f, 0.0f, 0.0f)
+				[
+					SNew(SButton)
+					.OnClicked_Lambda([this]() -> FReply
+					{
+						CloseSettingsPopup();
+						return FReply::Handled();
+					})
+					[
+						SNew(STextBlock)
+						.Text(FText::FromString(TEXT("Close")))
+						.Font(FCoreStyle::GetDefaultFontStyle("Bold", 11))
+						.ColorAndOpacity(FLinearColor::White)
+					]
+				]
+			]
 		];
 }
 
@@ -816,6 +935,25 @@ TSharedRef<SWidget> UPS_Editor_MainWidget_Legacy::BuildSceneButtons()
 						.Font(FCoreStyle::GetDefaultFontStyle("Regular", 10))
 					]
 				]
+				// Settings button — opens the global Settings popup
+				+ SHorizontalBox::Slot()
+				.AutoWidth()
+				.Padding(4.0f, 0.0f, 0.0f, 0.0f)
+				[
+					SNew(SButton)
+					.ToolTipText(FText::FromString(TEXT("Open scenario / session settings (dynamic nav, navmesh visu).")))
+					.OnClicked_Lambda([this]() -> FReply
+					{
+						OpenSettingsPopup();
+						return FReply::Handled();
+					})
+					[
+						SNew(STextBlock)
+						.Text(FText::FromString(TEXT("Settings")))
+						.Font(FCoreStyle::GetDefaultFontStyle("Regular", 10))
+						.ColorAndOpacity(FLinearColor(0.8f, 0.8f, 0.8f))
+					]
+				]
 				+ SHorizontalBox::Slot()
 				.AutoWidth()
 				.Padding(4.0f, 0.0f, 0.0f, 0.0f)
@@ -2868,6 +3006,55 @@ void UPS_Editor_MainWidget_Legacy::CancelBaseLevelPopup()
 	PendingBaseLevelSelection.Empty();
 }
 
+void UPS_Editor_MainWidget_Legacy::OpenSettingsPopup()
+{
+	if (SettingsPopup.IsValid())
+	{
+		SettingsPopup->SetVisibility(EVisibility::Visible);
+	}
+}
+
+void UPS_Editor_MainWidget_Legacy::CloseSettingsPopup()
+{
+	if (SettingsPopup.IsValid())
+	{
+		SettingsPopup->SetVisibility(EVisibility::Collapsed);
+	}
+}
+
+void UPS_Editor_MainWidget_Legacy::OnUseDynamicNavigationToggled(ECheckBoxState State)
+{
+	UPS_Editor_SpawnManager* SM = SpawnManager.Get();
+	if (!SM) return;
+
+	const bool bEnabled = (State == ECheckBoxState::Checked);
+	SM->bUseDynamicNavigation = bEnabled;
+	bSceneDirty = true; // user changed a per-scenario setting
+
+	// Apply live to the level's RecastNavMesh actors.
+	PS_Editor_NavUtils::SetDynamicNavigationEnabled(GetWorld(), bEnabled);
+}
+
+void UPS_Editor_MainWidget_Legacy::OnShowNavMeshToggled(ECheckBoxState State)
+{
+	UPS_Editor_SpawnManager* SM = SpawnManager.Get();
+	if (!SM) return;
+
+	const bool bVisible = (State == ECheckBoxState::Checked);
+	SM->bShowNavMesh = bVisible;
+
+	PS_Editor_NavUtils::SetNavMeshVisible(GetWorld(), bVisible);
+}
+
+void UPS_Editor_MainWidget_Legacy::ToggleShowNavMesh()
+{
+	UPS_Editor_SpawnManager* SM = SpawnManager.Get();
+	if (!SM) return;
+
+	SM->bShowNavMesh = !SM->bShowNavMesh;
+	PS_Editor_NavUtils::SetNavMeshVisible(GetWorld(), SM->bShowNavMesh);
+}
+
 void UPS_Editor_MainWidget_Legacy::OnCloseClicked()
 {
 	if (CloseConfirmOverlay.IsValid())

Unreal/Plugins/PS_Editor/Source/PS_Editor/UI/Widgets/PS_Editor_MainWidget_Legacy.h

@@ -107,6 +107,15 @@ private:
 	void ConfirmBaseLevelSelection();
 	void CancelBaseLevelPopup();
 
+	// Global Settings popup (per-scenario nav option + session-only navmesh visu).
+	TSharedPtr<SWidget> SettingsPopup;
+	void OpenSettingsPopup();
+	void CloseSettingsPopup();
+	void OnUseDynamicNavigationToggled(ECheckBoxState State);
+	void OnShowNavMeshToggled(ECheckBoxState State);
+	/** Toggle the navmesh visualization (P key handler). */
+	void ToggleShowNavMesh();
+
 	// Transform fields
 	TSharedPtr<SEditableTextBox> LocX, LocY, LocZ;
 	TSharedPtr<SEditableTextBox> RotX, RotY, RotZ;